Wetness sensing capabilities in an absorbent article has been a desirable and welcome feature for a variety of modern hygiene products. Disposable absorbent articles such as diapers, training pants, incontinence pads, and the like are highly absorbent and efficiently pull moisture away from the wearer, reducing skin irritation caused by prolonged wetness exposure. However, because these articles are so absorbent, wearers may not realize they have urinated, particularly if they are inexperienced toddlers who may not recognize the meaning of body sensations associated with urination. Thus, the wearer may not recognize their urination control failure or be aware the article should be changed. Furthermore, parents or caregivers may no recognize that the absorbent article requires changing.
Visual mechanisms have also been employed to signal the presence of wetness in absorbent articles. There are a large number of wetness sensing technologies that currently exist including electronic-based wetness sensors, color-based wetness sensors, and enzyme-based wetness sensors. However, all those wetness sensing technologies are not ideal and have one or more limitations. For instance, the electronic based wetness sensors are generally too expensive to be disposable, while enzyme-based wetness sensors may have stability issues. Water-soluble dye-based wetness indicators often lack high detection sensitivity desirable for new-born diapers. They also provide poor color contrast which sometimes makes signal reading difficult.
Thus, a need exists for wetness sensors that are cheap, safe, easy to be implemented in absorbent products, and easy to read. An absorbent article that incorporates such a sensor would be particularly beneficial.